Drinking water wells and boreholes


When sealing with DantoPlug bentonite pellets, you get the crucial advantage that the bentonite only really expands once it is in place down inside the borehole. At this point, the extremely dense material expands into any crevices and gaps that may exist in the borehole. The material’s ability to absorb water and swell remains unchanged over time. It is permanent, and the swelling capacity is many times greater than the volume of the void to be filled in order to create a seal.

As water-filled gaps and cracks form in the soil that surrounds the borehole, the bentonite will swell into them, maintaining the tight seal and adhesion between borehole and soil. This phenomenon is something that can only be achieved with a flexible, moving sealant material. The so-called chimney effect, where potential surface contamination runs down the borehole in the interface between a cementitious cured sealant and the soil, is thus permanently eliminated.


Bentonite is a natural material, and the properties and qualities of different bentonites can vary greatly.

There are many products on the market that contain bentonite of one kind or another, largely of unknown origin and quality – all with differing properties and characteristics.

The types of bentonite that are suitable for securing wells and boreholes against penetrating surface contamination and hydraulic short-circuiting are those with high swelling pressure. This kind of bentonite seals all the voids and cracks and keeps doing so. No other material can do that.

The bentonite that we use in all our products is exactly this type. We always use the same bentonite from our own quarry in Denmark. We are thus able to guarantee the quality and performance that we want for our customers.

A sustainable workplace

Dantonit in Odense is one of NCC’s sustainable workplaces. This means that our workplace meets a wide range of requirements set out in our sustainability framework, which includes the work environment, social inclusion, material and waste, climate and energy, compliance and portfolio execution.

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We develop and manufacture sustainable and waterproof bentonite solutions for:


If you require advice or a sounding board to choose the right bentonite solution, we’re always at your service. Fill out the form or contact us direct:

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